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Title Monopole Antenna Project Physics & Mathematics Antenna (Radio) Radio Technology Wavelength 1.6 MB 28
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MONOPOLE�ANTENNA Page�[2]�

Hashemite�University�|�Department�of�Electrical�and�Computer�Engineering

Monopole�Antenna�
Analysis,�Design�and�Simulation�using�Computer�

Supervisor:�

Dr.Omer�Al�Saraereh�

Students:�
Abdul�Karem��A.Al�Sbeeh��
Aiman�S.Resiq��
Ahmad�H.Zaid�
Ibrahim�M.Hruob�
Mohammed�Hisham�
Ismail�Abdel�Razzaq��
Yazeed�Sulaiman�
Jaafar�H.AbuRaad�

2007

Department�of�Electrical�and�Computer�Engineering�
Hashemite�University�

2007�

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MONOPOLE�ANTENNA Page�[3]�

Hashemite�University�|�Department�of�Electrical�and�Computer�Engineering

���������������������������Fig.1:�Monopole�Antenna�

Introduction
Chapter�I�

Over�view�about�monopole�Antenna

Now�days,�wireless�communication�systems�are�becoming�increasingly�popular.�However,�the�technologies�for�wireless�
communication�still�need�to�be�improved�further�to�satisfy�the�higher�resolution�and�data�rate�requirements.�In�the�
communication�system�the�more�things�is�look�to�is�the�coast�and�low�power�device�and�it�is�the�monopole�which�
previous�thing�is�used�and�still�be�improve�for�the�communication�system.�

Monopole�is�a�type�of�the�radio�antenna�formed�by�replacing�one�half�of�a�dipole�antenna�with�a�ground�plane�at�
right�angles�to�the�remaining�half.�If�the�ground�plane�is�large�enough,�the�monopole�behaves�exactly�like�a�dipole,�
as�if�its�reflection�in�the�ground�plane�formed�the�missing�half�of�the�dipole.��

This� study� is� restricted� to� a� monopole� geometry� consisting� of� a� vertical� cylindrical� element� at� the� center� of� a�
perfectly� conducting,� infinitely� thin,� circular� ground� plane� in� free� space.� This� geometry� is� of� interest� because� its�
radiation� pattern� is� uniform� in� the� azimuth� direction� and� because� its� electrical� characteristics� are� primarily� a�
function�of�only� three�parameters,�namely,� the�element� length,� the�element�radius,�and� the�ground�plane�radius,�
when� each� is� normalized� to� the� excitation� wavelength.� Therefore,� this� geometry� is� conducive� to� analysis,�
experimental�verification,�and�standardization.�

A� typical� feed� for� the� monopole� antenna� is� a�
coaxial� line�with� its� inner�conductor�connected�
through� a� hole� in� the� ground� plane� to� the�
vertical� monopole� element� and� its� outer�
conductor� connected� by� means� of� a� flange� to�
the� ground� plane.� Typically,� the� inner�
conductor’s�diameter� is�equal�to�the�monopole�
element’s� diameter� and� the� outer� conductor’s�
diameter� is� equal� to� the� ground� plane� hole�
diameter.�Unless�stated�otherwise,�such�a� feed�
will� be� assumed� in� this� study.� The� ratio� of� the�
coaxial� line’s� outer�to�inner� conductor�
diameters� affects� the� antenna’s� input�
impedance,�but�only�significantly�for�a�relatively�
thick�monopole�element�on�a�very�small�ground�
plane.�

For� the� idealized� case� of� a� ground� plane� of�
infinite� extent� and� infinite� conductivity,� the� monopole� antenna� may� be� modeled� by� the� method� of� images� as� a�
dipole�with�one�half�the�input�impedance�and��

double� the� peak� directivity� of� the� dipole.� The� infinite� ground� plane� prevents� monopole� radiation� into� the�
hemisphere� below� the� ground� plane,� but� allows� a� radiation� pattern� identical� to� that� of� the� dipole� in� the� upper�

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MONOPOLE�ANTENNA Page�[15]�

Hashemite�University�|�Department�of�Electrical�and�Computer�Engineering

TMn0�Spherical�Wave�Modes�

The�solution�of�the�vector�Helmholtz�equation�in�spherical�co�ordinates,�subject�to�the�constraints�of�vertical�
polarization,�outward�traveling�waves,�and�an�Omni�directional�pattern�in�the�azimuthally�direction,�is�a�set�of�
orthogonal�TMn0�spherical�wave�modes.�The�resulting�fields�evaluated�at�a�radius�r�=�ro�are�given��

��

��

The�radial�wave�impedance�Zn0(P)�of�the�Poynting�vector�in�the�outward�radial�direction�for�each�mode�is�defined�as�
��

��

The�Poynting�vector�is�not�sufficient�to�characterize�the�mode�Qn0�because�its�imaginary�part�is�proportional�to�the�
difference�(rather�than�the�sum)�of�electric�and�magnetic�stored�energies.�The�radial�wave�impedance�and�all�its�
derivatives�with�respect�to�frequency�are�sufficient�but�not�convenient�to�characterize�Qn0�of�the�TMn0�mode.��

��

Fig.5:�Radiating�regions.��

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MONOPOLE�ANTENNA Page�[16]�

Hashemite�University�|�Department�of�Electrical�and�Computer�Engineering

Design�and�Simulation�an�Monopole�antenna�
“Using�CST�2006B�software�” Chapter�

III�

Monopole�Antenna�Configurations:
4.1�Type�One:�

� Soled�Monopole�with�feeding�from�origin.�

Fig.6�Monopole�Antenna�soled�

Fig.7�Monopole�Antenna�Feeding�

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MONOPOLE�ANTENNA Page�[28]�

Hashemite�University�|�Department�of�Electrical�and�Computer�Engineering

2. Solve�the�problem�of�tuning�instabilities�arising�from�environmental�changes�in�humidity�and�temperature�in�
addition�to�that�of�ground�plane�size.�

3. Improve�the�antenna�radiation�efficiency,�since�it�would�not�be�necessary�to�load�the�antenna�circuit�with�
antenna�loss�in�order�to�provide�tuning�stability.�

An�alternative�to�the�implementation�of�different�tuning�words�for�different�platforms�might�be�to�utilize�a�different�
antenna�element,�such�as�a�dipole,�whose�input�impedance�might�not�be�as�sensitive�to�ground�plane�size�as�that�of�
a�monopole.�However,�even�if�such�an�element�would�prove�to�have�better�tuning�stability�with�varying�ground�
plane�size�and�to�have�the�desired�gain�pattern�characteristics,�it�is�not�clear�how�such�an�alternative�would�solve�the�
problem�of�tuning�instabilities�arising�from�changes�in�humidity�and�temperature�without�having�to�load�the�antenna�
circuit�with�antenna�loss�in�order�to�provide�tuning�stability.�

Consequently,�implementation�of�different�tuning�words,�by�sensing�in�real�time,�the�impedance�mismatch�and�then�
modifying�the�tuning�word�at�a�given�frequency�to�minimize�the�impedance�mismatch,�is�a�preferable�design�
objective.�

Such�an�objective�has�been�realized�at�HF�frequencies�and�for�a�radio�frequency�
(RF)�power�level�of�400W�with�sensing�and�tuning�times�of�approximately�
20msec�and�1�sec,�respectively,�by�a�circuit�comprising�a�directional�coupler,�digital�processor,�and�
electromechanical�switches.�The�substitution�of�p�type/�intrinsic�type/n�type�(PIN)�diode�switches�for�the�
electromechanical�switches�might�prove�to�be�a�feasible�technique�for�achieving�such�an�objective�with�a�tuning�
time�of�less�than�1�msec,�provided�that�the�inter�modulation�products�generated�by�the�use�of�such�switches�are�not�
excessive�for�the�intended�application.�

Electronically�tunable�helical�elements�utilizing�PIN�diode�switches�have�been�successfully�designed�and�tested�in�an�
open�loop�mode�with�an�RF�power�level�of�10Wat�VHF�frequencies�and�400Wat�HF�frequencies.�
Closed�loop�operation�is�compatible�with�the�fast�tuning�capability�of�PIN�diode�switches�but�its�realization�has�not�
yet�been�reported�in�the�open�literature.��

We�can�see�from�design�an�monopole�antenna�in�chapter�3�that�monopole�antenna�made�from�cylindrical�materials�
that�produce�radiation�Pattern�more�better�than�in�monopole�Antenna�made�from�soled�materials.�See�the�figures��

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MONOPOLE�ANTENNA Page�[29]�

Hashemite�University�|�Department�of�Electrical�and�Computer�Engineering

References
Chapter�V

Books:�

1. JH�Richmond.�Monopole�Antenna�on�Circular�Disk.�Technical�Report�711639�1.�Electro�Science�
Laboratory,�July�1979.�See�also�IEEE�Trans�Antennas�Propagation�AP�32(12):1282�1287,�1984.�

2. A�Leitner,�RD�Spence.�The�oblate�spheroidal�wave�functions.�Franklin�Inst�J�249(4):299–321,�1950.�
3. JE�Storer.�The�impedance�of�an�antenna�over�a�large�circular�screen.�J�Appl�Phys�22(Aug):1058–

1066,�1951.�See�also�Techical�Report�No�119,�Cruft�Laboratory,�Harvard�University,�Nov�1950.�
4. KH�Awadalla,�TSM�Maclean.�Monopole�antenna�at�the�center�of�a�circular�ground�plane:�Input�

impedance�and�radiation�pattern.�IEEE�Trans�Antennas�Propagation�AP�27(2):151–153,�1979.�
5. RS�Elliot.�Antenna�Theory�and�Design.�Englewood�Cliffs,�NJ:�Prentice�Hall,�1981,�pp�290–291.�
6. CA�Balanis.�Antenna�Theory:�Analysis�and�Design.�New�York:�Harper�and�Row,1982,�p�315.�
7. L�Brillouin.�Origin�of�radiation�resistance.�Radioelectricite�3:147–152,�1922.�
8. JA�Stratton.�Electromagnetic�Theory.�New�York:�McGraw�Hill,�1941,�pp�454–457.�
9. Printed�circular�disc�monopole�antenna�for�ultra�wideband�applications�J.�Liang,�C.C.�Chiau,�X.�Chen�

and�C.G.�Parini.�

Word�Wide�Web�(WWW):�

1. http://www.antennex.com/preview/monopole.htm�
2. http://antennasystems.com/saber/monopoles/monopoles.html�
3. http://www.mwjournal.com/Journal/article.asp?HH_ID=AR_689�
4. http://www.antenna.be/vm.htm�
5. Wikipedia,�the�free�encyclopedia.com�